Can End Having An Annular Rib

ABSTRACT

A can end includes an annular rib that may be inclines. Some embodiments of the bead form a teardrop shape. The bead of other embodiments are open. A combination beverage can end and can body, and the tooling and method for forming the can end are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This claims the benefit of U.S. Patent Application Ser. No. 61/549,797 filed Oct. 21, 2011, the disclosure of which is hereby incorporated by reference as if set forth in its entirety herein.

This invention relates to metal packaging and more particularly to a light weight can end, a method and apparatus for its manufacture, and a can having the can end. The invention is particularly concerned with beverage cans for carbonated drinks, and the provision of can ends therefor.

BACKGROUND

Lightweight beverage can ends, such as those having an inclined chuck wall, have become commercially popular. The first of such ends is disclosed in WO96/37414, sold under the tradename SUPEREND, which discloses a can end comprising a peripheral cover hook, a chuck wall dependent from the interior of the cover hook, an outwardly concave reinforcing bead extending radially inwards from the chuck wall, and a central panel supported by an inner portion of the reinforcing bead characterized in that the chuck wall is inclined to an axis perpendicular to the exterior of the central panel at an angle between 20 degrees and 60 degrees. WO96/37414 shows a conventional annular reinforcing bead between the chuck wall and that center panel.

The SUPEREND end as disclosed in WO96/37414 provided an improved strength to metal volume ratio in comparison to earlier can ends at least in part because the angle of the chuck wall allowed the central panel to be of a smaller diameter than earlier can ends and which, when the can end was seamed onto a can and pressurized, transmitted a lower force via the reinforcing bead to the chuck wall. Also, the angle of the chuck wall was suited to transmit the forces generated by pressurisation to the seam with little distortion.

However, when this can end was submitted to excess or localised pressure, often resulting from an impact if the can was dropped, the chuck wall would flip outwards, creating a pointed pucker known as a “peak”, wherein the metal was prone to fracture and allow the contents of the can to leak. Such a failure became known as “peak and leak”.

Patent Applications WO 2006/050465 and US20100044383, each of which is assigned to the present assignee, describe control features to prevent the formation of such peaks. However, the benefit of such control features is partly offset by a general reduction in the pressure at which the end would permanently distort.

The technical advances of the SUPEREND can end spurred competing canend development, such as that described in U.S. Pat. Nos. 7,819,275 and 6,702,142. Each of these can ends has a reinforcing bead having a rounded bottom and sidewalls that are either vertical or open outwardly. The inventors understand that these ends have a failure mode in which the reinforcing bead fails approximately vertically upwardly. In many ends, over pressure results in upward deformation of the center panel and ovality in the end, possibly resulting from anistropic properties of the end itself. At some location about the circumference, the opposing vertical sidewalls move horizontally together, which is followed by eversion at least at that the of the narrowed horizontal spacing between the sidewalls, and thus, failure.

The commercial can end of WO 96/37414 is conventionally formed in a single press operation. The forming is carried out simply by axially moving several concentric tools, some of which are resiliently loaded by pistons or springs. Subsequently, further scoring, embossing, lettering and tab attachment operations are typically carried out by well-known processes.

WO 2005/113351 describes a can end comprising a center panel, a circumferential chuck wall and a transition wall, wherein the transition wall comprises a folded portion. Several methods are described whereby such a fold might be manufactured, including either a second forming operation or a squeezing operation as shown in FIG. 49-52 or 53-57 of WO 2005/113351, wherein the metal is collapsed in an uncontrolled “free-form” manner. The end disclosed in WO 2005/113351 has not been a commercial success.

Connected with the strength of a can end is the resistance of the can end to outward deflection of the central panel when the can is internally pressurized. The central panel, as well as any opening tab formed on the outer surface of the panel, is typically recessed relative to the plane of the outer edge of the seam which joins the can end to the can. As the pressure differential between the inside and the outside of the can increases, the central panel tends to dome and bulge outwardly. This will tend to push the central panel and any opening tab thereon outwardly relative to the seam, and may cause the opening tab to become exposed beyond the plane of the seam. In this condition, the opening tab is prone to snagging, which may interfere with further processing and packaging, and may lead to unintentional opening of the can.

Strength, light weight, and diminished peak and leak phenomenon have been longstanding goals of can end engineering.

SUMMARY OF INVENTION

The present invention provides a can end comprising a peripheral cover hook, a chuck wall dependent from the interior of the cover hook, an outwardly concave rib extending radially outwards from the lower end of the chuck wall, and a central panel supported by the lower portion of the rib characterized in that the chuck wall is inclined to an axis perpendicular to the exterior of the central panel at an angle between 20 degrees and 60 degrees, and that the central panel is connected to the reinforcing bead by an outwardly convex curved portion.

When the can end is pressurized, upward doming of the center panel is limited by resistance from the outwardly convex curved portion, which joins it to the outwardly concave reinforcing bead. Upward doming may also be limited by mutual contact between the outer surfaces of the reinforcing bead as the center panel moves upwards.

The inventors surmise that “peaking” is avoided or diminished by the circular stiffness of the reinforcing bead and the generation of progressive deformation of the chuck wall as over-pressurization occurs.

If an aperture is formed, offset from the center, in the center panel of the can end and is closed and pressurized, distortion of the aperture shape is limited by resistance from the outwardly convex curved portion, which joins the central panel to the outwardly concave reinforcing bead.

The can end of the invention may comprise additional annular features within the chuck wall.

The can end of an aspect of the present invention can be considered as having a center panel structure, including a substantially flat center panel and a radially outwardly, axially inwardly sloping panel wall, and a chuck wall structure including a chuck wall with a curved transition at its radially- and axially-inner end and connected at its radially- and axially-outer end to a joining portion. The center panel structure advantageously exhibits a larger outer diameter than the inner diameter of an opening formed by the radially- and axially-inner edge of the chuck wall structure, and lies at least partially axially inside the chuck wall structure so that the chuck wall structure resists the center panel structure from passing axially outwardly through the opening when a can including the can end is pressurized.

Features of the can end include an annular rib surrounding the center panel structure acting as a reinforcing ring to resist outward doming of the center panel which tends to pull the peripheral edge of the center panel radially inwardly.

The annular ring is connected between the center panel structure and the chuck wall structure, and extends radially outwardly relative to an inner peripheral edge of the surrounding chuck wall structure. The rib is concavely curved facing radially inwardly.

In preferred embodiments, the radially outwardly, axially inwardly sloping panel wall forms, together with the center panel, a domed structure that is convex in the axially outward direction to function as a pseudo-pressure vessel to transfer forces from the center panel to the annular bead without inducing substantial bending moments in the center panel. The sloping panel wall is preferably convexly curved, and may be continuously curved to blend at one end with the center panel and at the other end with the rib.

The curved transition at the radially- and axially-inner end of the chuck wall structure is also preferably continuously curved to blend with the chuck wall and the opposite end of the rib. Alternatively, the curved transition may include one or more straight portions. The curved transition is convexly curved, facing in the radially inward direction, and acts as an annular rib strengthening the opening formed by the radially inner edge of the chuck wall structure.

The can end may be configured so that when a can including the can end is pressurized sufficiently to deform the can end, the can end will exhibit a progressive failure mode. This may be achieved by the panel wall and the transition at the radially inner edge of the chuck wall structure both being convexly curved and arranged so that, as the can end is deformed axially outwardly, they will kiss, cam or roll against or relative to each other, in many cases without the can end failing at a unique circumferential point of weakness.

The inventors surmise that improved performance of the can end will allow it to be manufactured from thinner sheet metal, and its geometry may be adjusted to use the same area of metal as or less than that of can ends of the prior art.

Inner center panel tool of an aspect of the present invention has a peripheral forming surface that slopes radially outwardly and axially inwardly from a central panel region. The peripheral surface preferably extends gradually axially inwardly from the peripheral edge of the central panel region in the radially outward direction. The sloped forming surface is preferably continuously curved, and may, for example, exhibit an elliptical curvature or a constant radius of curvature, although the invention is not limited to this structure. At the radially outer edge of the sloped forming surface, the inner center panel tool has a concave annular ring with a radius of curvature that is small compared to the length of the convex forming surface, and which promotes the formation of an annular bead when a blank is pressed against the inner center panel tool. The concave annular recess is preferably curved, and in some embodiments may have a substantially constant radius of curvature.

The concave annular recess terminates at the radially outer edge of the inner center panel tool in an axially outward peak. The peak may advantageously blend the curvature of the concave annular recess with the radially inner wall of an inner wall tool that is arranged to substantially adjacently surround the inner center panel tool during formation of a can end. Such tooling according to the present invention defines an annular recess, axially inwardly of the center panel region of the inner center panel tool, between the inner center panel tool and the inner wall tool, into which axially drawn material of a blank may be reformed under axial compression. The peripheral surface may advantageously be sloped radially outwardly and axially inwardly in such a manner that, when a blank is pressed against the inner center panel tool, a center panel and/or a panel wall region of the blank will be brought into tension.

Tooling according to the present invention may include the inner center panel tool and inner wall tool on an axially inner side, opposed to outer tools including an outer center panel tool and at least one outer wall tool. The outer center panel tool has a diameter smaller than the diameter of the inner center panel tool, and may be at least partially disposed inside the inner wall tool to leave an annular gap. A blank which is axially outwardly drawn across the annular gap may be reformed against the inner center panel tool in a single axial compression motion, by moving the opposed inner and outer wall tools axially inwardly relative to the opposed inner and outer center panel tools. A preferred characteristic of the tooling is that the annular recess formed by the inner tools opposes the annular gap between the outer center panel tool and the inner wall tool.

The present invention also provides a method for the manufacture of that can end by blanking and drawing the can end and reforming its center panel to create its reinforcing bead, in a single press operation.

This method helps avoid doming of the center panel when subsequently pressurized, by creating tensile stresses within the center panel during reforming.

The method of manufacturing a can end according to the present invention involves axially compressing an axially drawn blank to reform the axially drawn portion in a single step to produce the panel wall, annular bead and curved transition which extend between the center panel and chuck wall of the can end. Advantageously, the step of axially compressing the blank serves to bring the center panel region of the blank under tension, increasing the rigidity and reducing floppiness of the center panel of the can end.

The preferred reforming method desirably imparts a series of preliminary curves at different stages, which, under further axial compression, collapse and plastically deform to form the desired can end wall features. The method may also involve pressing the axially extending wall of the drawn blank into an annular recess that includes a curved concave annular recess which tends to promote formation of the tightly rolled annular bead.

Advantageously, the tooling and manufacturing method of the present invention can be implemented with existing can end pressing machines, and so the can ends of the present invention can be made without substantial changes to the manufacturing equipment or the need to buy new manufacturing plant.

Alternatively, the reforming method may be carried out in a separate press or tooling station to that in which the blank is drawn. Carrying out the reforming operation in a separate press may be desirable if it is easier to handle the taller drawn blank through other machinery for carrying out related operations (for example, to curl, score, emboss, etc.) than the shorter reformed end. In this case, the reforming process can be used to remove any slackness that may arise in the center panel, caused, for example, by a scoring or embossing operation. The can end may be formed of conventional aluminum, or alternatively of steel.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-sectional view of a conventional can end in a plane through the can end which includes the central axis of rotation of the can end;

FIG. 2 shows a cross-sectional view of an embodiment of a can end according to the present invention in a plane through the can end which includes the central axis of rotation of the can end, omitting any detailed features of the center panel of the can end;

FIG. 3 shows a plan view of the can end shown in FIG. 2;

FIG. 4 shows a similar cross-sectional view to that of FIG. 2, of the can end of FIGS. 2 and 3;

FIG. 4A shows an enlarged view of the portion of the cross-sectional view circled in FIG. 4;

FIG. 5 shows an enlarged view in the same cross-sectional plane as FIGS. 4 and 4A, illustrating detail of a bead and chuck wall portion of the can end;

FIG. 5A shows an enlarged, cross sectional view of a second embodiment of the rib and adjacent structure;

FIG. 5B shows an enlarged, cross sectional view of a third embodiment of the rib and adjacent structure;

FIG. 5C shows an enlarged, cross sectional view of a fourth embodiment of the rib and adjacent structure;

FIG. 5D shows an enlarged, cross sectional view of another embodiment of the rib, panel wall structure, and adjacent structure;

FIG. 6 shows a superimposed sequence of schematic cross-sectional views of the embodiment of the can end of FIGS. 2 to 5 double-seamed onto one axial end of a can body of a can, in a plane through the can which includes the central axis of rotation of the can body and can end, illustrating deflection of the can end due to internal pressurization of the can, together with an enlargement of the circled portion which includes the bead and chuck wall portion of the can end;

FIG. 6A shows, in sequence, separate schematic cross-sectional views (a) to (d) of each superimposed image of FIG. 6, as the can end deflects under increasing internal pressurization of the can, together with corresponding enlarged views of the circled portion of each image which includes the bead and chuck wall portion of the can end;

FIGS. 6B and 6C show corresponding views as for FIGS. 6 and 6A, for an alternative embodiment in which the can end is initially formed with the panel wall and curved transition region touching, so that the mouth is closed, and where the mouth remains closed as the can end deflects under pressurization;

FIGS. 6D and 6E show corresponding views as for FIGS. 6 and 6A, for an alternative embodiment in which the can end is initially formed with the panel wall and curved transition region not in contact, so that the mouth is open, and where the mouth remains open as the can end deflects under pressurization;

FIG. 7 shows another enlarged detail view, similar to that of FIG. 5, illustrating certain important features of the embodiment of the can end of FIGS. 2 to 6, and of an embodiment of tooling according to the present invention which may be used to form such a can end from a blank, in a plane through the can end which includes the central axis of rotation of the can end;

FIG. 8 is a similar view to that of FIG. 7, illustrating further features of the tooling which may be used to form the can end;

FIGS. 9, 10 and 11 show an embodiment of tooling according to the present invention, suitable for forming the can end of FIGS. 2 to 7 from a blank, at different axial positions which illustrate forming an annular bead of the can end under axial compression;

FIGS. 9A to 11A show enlarged cross-sectional views of the circled portions of the tooling of FIGS. 9, 10 and 11, respectively, together with a blank being formed into the can end, in a plane through the can end which includes the central axis of rotation of the can end;

FIG. 12 shows an enlarged cross-sectional view of a can end and the related tooling of FIGS. 7 to 11, in a plane through the can end which includes the central axis of rotation of the can end, illustrating schematically how material flow is induced in the blank to bring the center panel and/or panel wall portions under tension during axial compression for forming a can end from the blank;

FIGS. 13 to 17 show a series of enlarged cross-sectional views of an embodiment of tooling according to the present invention in a plane through the tooling which includes a central axis of rotation of the blank from which an embodiment of a can end according to the present invention is formed, and sequential steps in the formation of such a can end thereby;

FIG. 18 shows an enlarged view, similar to FIG. 4A, of the bead and chuck wall portion of another embodiment of a can end according to the present invention, where side walls defining the bead mouth are parallel;

FIG. 19 shows an enlarged view, similar to FIG. 4A, of the bead and chuck wall portion of a further embodiment of a can end according to the present invention, where side walls defining the bead mouth are diverging;

FIG. 20 shows an enlarged view, similar to FIG. 4A, of the bead and chuck wall portion of still another embodiment of a can end according to the present invention, where the panel wall is substantially straight between the center panel and the bead; and

FIG. 21 shows an enlarged view, similar to FIG. 4A, of the bead and chuck wall portion of still another embodiment of a can end according to the present invention, where a cover, label, token or tab is schematically indicated as being provided in the concave annular structure formed with the bead.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, a can end is formed from a circular blank of material, exhibiting a central axis of rotational symmetry, shown as axis X in FIGS. 3 and 4. This axis of the blank, which corresponds to the central axis of a can end formed from the blank, is used throughout the present description to define the axial direction of the blank, the can end, a can body, and a can having the can end of the present invention attached to the can body, as well as the central axis of associated tools and tooling by which the can end may be formed. In the embodiments illustrated and described herein, these all have a common central axis.

The upper side of the can end shown in FIG. 2 corresponds to the side of the can end which will be exposed, externally, after the can end has been joined to one axial end of a can body. Similarly, the lower side of the can end shown in FIG. 2 corresponds to the side of the can end which will be inside the can, after it has been joined to one axial end of a can body. These two sides of the can end are therefore referred to, correspondingly, as the outer side and the inner side of the can end. Likewise, throughout the present description, references to the outer side and to the outer axial direction are made with respect to the direction which the outer side of the can faces, whilst references to the inner side or inner axial direction are references to the direction in which the inner side of the can faces.

A similar convention is used to define the tools and tooling by which the can end according to the present invention may be made. Accordingly, an “inner tool” is a tool which opposes an inner side of a blank in order to form the can end, whilst an “outer tool” is a tool which opposes the outer side of the blank for forming a can end

This frame of reference, and such labelling, will be used throughout, unless it is explicitly stated that a non-axial direction is being described. For example, in the radial direction, reference will be made to the radially inward and radially outward directions, or to the radially inside or radially outside surfaces of various components, in which case it is clear that the radial direction, rather than the axial direction, is being described.

FIGS. 2 to 5 all illustrate a can end 10 which is an embodiment of the present invention. The same can end 10 is shown attached to a can body in FIG. 6, and is the can end resulting from the use of the tools and tooling and associated method which will be described in relation to FIGS. 7 to 17

In this regard, the embodiment of a beverage can end shell 10 is illustrated in FIGS. 2 through 5. End shell 10 in FIGS. 2 through 4 is shown before its conversion into a finished end by the formation of a rivet, application of a pull tab, and scoring to create a tear panel (not shown in FIGS. 2 through 4). It is understood that the present invention encompasses finished ends. Further, reference to a can end as used herein encompasses finished can ends and is not limited to can end shell structure before the conversion process

Referring to FIG. 2, there is shown a cross-sectional view of a can end 10 according to an embodiment of the present invention, in a plane through the can end which includes the central axis X, being an axis of rotational symmetry, of the can end 10.

Can end 10 shown in FIGS. 2 through 4 includes a peripheral curl 12, a wall, such as chuck wall 14, a rib 16, a panel wall 18, and a center panel 20. Peripheral curl 12 includes a cover hook 24 at its periphery and a seaming panel 26 that extends inwardly from cover hook 24. Preferably, peripheral curl 12 has a conventional configuration for engaging a flange of a beverage can body 110 such that end 10 and a can body 110 can be formed together in a conventional double seaming process. The double seam is illustrated in FIG. 6 by reference numeral 120.

Chuck wall 14 extends radially inwardly and axially inwardly (that is, downwardly in the orientation of the figures) from a radially inner end of peripheral curl 12, and preferably from the radially inner end of seaming panel 26. Chuck wall 14 is shown in the figures inclined at a wall angle Θ and straight. The present invention is not limited to straight chuck walls; rather the term “wall” or “chuck wall” as used herein encompasses structures that are formed by more than one part or otherwise have more complex configurations, such as all or part of the walls disclosed in Patent Publication WO1998034743, entitled “Can End” and assigned to Crown Cork & Seal Technologies Corp; U.S. Pat. No. 7,673,768 entitled “Can Lid Closure” and assigned to Metal Container Corp; and United States Patent Publication US20110031256, entitled” Can Shell and Double-Seamed Can End” and assigned to Container Development Ltd.

Measurement of wall angle Θ for walls having complex geometries can be measured by a straight line drawn between the (i) uppermost portion of the chuck wall where it joins the peripheral curl and (ii) the lowermost portion of the chuck wall where the wall joins the transition between the wall and the rib.

The present invention encompasses any wall angle Θ and chuck wall configuration that provides sufficient space for rib 16 upon seaming on to a can body 110. Wall 14 and rib 16 preferably are configured so that the neck of the can body does not contact the radially outermost portion of rib 16. The inventors surmise, however, that a range of angles of between about 20 degrees and about 70 degrees, more preferably between about 25 degrees and about 60 degrees, even more preferably between about 33 degrees to about 50 degrees, and most preferably about 45 degrees will provide improved pressure performance, although an inclined wall is optional.

Rib 16, as illustrated in FIGS. 2 through 4, includes a rib inner wall 44, a rib base 46, a rib outer wall 48, and a transition 50. It is understood when referring to inner and outer walls 44 and 48 that the terms “inner” and “outer” refer to radially inner and radially outer orientations. The structure of rib 16 preferably converges to form a mouth M, which can be defined as the narrowest portion of rib 16 outside of rib base 46. Mouth M in most structures of rib 16 will be defined between opposing walls 44 and 48, and the present invention encompasses other structure, such as mouth M being formed between inner wall 44 and transition 50.

Rib 16 extends axially inwardly (that is, downwardly in the orientation of the figures) and generally radially outwardly. Transition 50 is a convex portion that preferably is tightly rolled or curved and extends from the bottom end of chuck wall 14. It is understood that the structure of rib 16 encompasses a configuration in which transition 50 merges directly into rib base 46. Alternatively, rib outer wall 48 may connect the ends of transition 50 and rib base 46.

Preferably, rib 16 has a cross section that is uniform about the circumference such that end 10 has rotational symmetry about central vertical axis X, although rotational symmetry it is not essential.

In the embodiment shown in FIGS. 2 through 4A, panel wall 18 extends radially outwardly toward rib 16 and into the structure of rib 16 such that rib inner wall 44 is formed as a lower portion of panel wall 18. Thus, rib 16 may encompass a portion of panel wall 18. Alternatively, the panel wall 38 may terminate outside of rib 16, such as at or axially outwardly of (that is, above in the orientation of the figures) mouth M and such that rib inner wall 44 is not part of panel wall 18, but rather inner wall 44 may be its own structure that extends from panel wall 18. For example, the present invention encompasses a curved, convex structure at the radially outward end of panel wall 18 (not shown in the figures).

Rib base 46 is a tightly rolled or curved portion that is concave relative to the end's exterior or axially outer position. Preferably, rib base 46 has an approximately constant curvature for at least 180 degrees in cross section. Rib inner wall 44 is convex and merges into base 46 at a first traverse point 54. Rib base 46 merges into convex rib outer wall 48 at a second traverse point 56. The terms “concave” and “convex” referred to herein are determined based on the origin of the radius of curvature local to the curve. “Convex” is used where the origin of the radius of curvature is on the axially inner side of end 10 (that is, on the inside side of end 10). “Concave” is used where the origin of the radius of curvature is located on the axially outer side of end 10 (that is, on the outside side of end 10). Thus, traverse points 54 and 56 are points at which the tangents to the curves defined by rib 16 cross the curve defined by rib 16.

The inventors surmise that the inclination of rib 16 enhances strength, as explained more fully below, as the sloped panel wall 18 and center panel 20 approximate the behaviour of an ideal pressure vessel by transmitting the tensile forces in the center panel from the center panel 20 to the rib 16 under tension and with minimal induced bending moments. Without intended to be bound by any particular definition, three particular definitions of the angle of inclination are defined below.

Rib 16 preferably is inclined relative to vertical axis X by an angle α of inclination measured on the radially inner wall 44. The inner wall inclination angle α is measured from a vertical line in the radially outward direction around to the tangent to the curve defined by rib 16 at first traverse point 54. As best shown in FIG. 5, the angle α is approximately 135 degrees. The angle α is preferably less than 180 degrees, more preferably no more than 150 degrees. Further, angle α is preferably more than 95 degrees, and more preferably at least 105 degrees, and more preferably at least than 115 degrees.

Rib 16 preferably is inclined relative to vertical axis X by an angle β measured on the radially outer wall 48, which is measured at the opposite end of the rib base 46 from inner wall inclination angle α. Outer wall inclination angle β is defined by the tangent to the curve defined by rib 16 at traverse point 56, measured in the cross-sectional plane which includes the central axis of rotation X of the can end 10. The angle β is measured from a vertical line moving in the radially inward direction (that is, counter clockwise in the orientation show in FIG. 5).

In the embodiment shown in FIG. 5, the angle β is approximately 90 degrees, and in general is preferably more than 45 degrees, more preferably more than 60 degrees. In the case of any discrepancy over the angle taken at the inner or outer surface of the wall, the angle of the tangent to the inner side surface should be taken.

Also, the inclination of rib 16 may be determined by a line drawn through mouth M that is equidistant between the opposing sides, such as sidewalls 44 and 48, and that bisects the area with rib 16. More specifically, a point P may be defined by drawing a line across mouth M, which for this purpose may be defined as the narrowest point of rib 16 outside of base 46. The point P on the line is equidistant from the opposing sidewalls forming mouth M. The area within rib 16 below the line drawn at mouth M defines the internal area of rib 16 for this purpose. The line R is drawn through point P such that R divides the rib area into equal portions. Line R defines the angle ρ of the rib area, measured clockwise from the vertical.

The rib area angle ρ is preferably less than 180 degrees, more preferably no more than 150 degrees. Further, rib area angle ρ preferably is more than 90 degrees, and more preferably more than 115 degrees.

In another aspect of the structure, rib 16 can be seen to substantially inscribe a circle. Due to the axially inwardly and radially outwardly sloping nature of the panel wall 18, combined with the radially outwardly extending disposition of the rib 16, the mouth m is located axially outwardly and radially inwardly of the inscribed circle. In this regard, the radially outermost portion of mouth M defines a circumference that preferably is less than the circumference defined by the radially outermost portion of rib 16.

Panel wall 18 extends from within or from rib 16 axially outwardly and radially inwardly. Panel wall 18 has a panel wall body 36 that is bounded by a panel wall, an axially outer, radially inner end 34 and a panel wall axially inner, radially outer end 38. Thus, as shown in cross sectional view, FIGS. 2, 4, and 4A, panel wall 18 defines a convex curve such that it has a center of radius of curvature that is on the axially inner side of the end—that is, that gradually extends away from the center panel 20 in the axially inward direction and radially outward direction. In three dimensions, panel wall 18 shown in the figures forms a portion of a dome.

In the example shown in FIG. 2, the curved annular panel wall 18 is of substantially constant curvature, and blends at its radially inner end 34 into the flat center panel 20. The present invention is not limited to this structure, and encompasses a panel wall that has a constantly varying radius (as for example, an involute of a circle), a series curves each of which has a curvature that is fixed and/or varying, a single straight section (as approximately described below with respect to FIG. 5D), several discrete straight sections, and any combination thereof. The term “sloped” is used to encompass any of the above configurations of panel wall so long as the trend is generally axially inwardly (that is, downwardly as oriented in the figures), even if not monotonically axially inwardly. Because of the slope of panel wall 18, rib 16 is located axially inwardly (that is, positioned below in the orientation of FIGS. 2 through 4A) relative to center panel 20 or a plane defined by center panel 20.

Center panel 20 is shown in the FIGS. 2 through 4A as essentially flat without a rivet, tab, score, embosses or debosses, or ribs. The present invention encompasses structure common to finished, unseamed ends, especially the structures associated with common panel configurations known as Stolle-style ends and DRT-style ends, which are understood by persons familiar with can end technology. Further, the present invention encompasses ends having an opening for receiving a resealable device, such for the end shown in Patent Publication Number WO2007/128810.

The present invention encompasses additional configurations of an annular rib and its adjacent parts. For example, FIG. 5A illustrates a second embodiment can end 10 a having a peripheral curl 12 a, a wall, such as chuck wall 14 a, a rib 16 a, a panel wall 18 a, and a center panel 20 a. Peripheral curl 12 a, wall 14 a, panel wall 18 a and center panel 20 a are nominally the same as the components described for can end 10 of FIG. 5. Rib 16 a includes a rib inner wall 44 a, a rib base 46 a, a rib outer wall 48 a, and a transition 50 a. The structure of rib 16 a, such as walls 44 a and 48 a, and/or inner wall 44 a and transition 50 a, preferably converge to form an enlarged mouth M (that is, enlarged relative to the mouth of the embodiment of FIG. 5), which can be defined as the narrowest portion of rib 16 a outside of rib base 46 a, which in most structures of rib 16 a will be defined between opposing walls 44 a and 48 a. Rib 16 a extends downwardly and generally radially outwardly from a curved transition 50, which extends from chuck wall 14 a. In this regard, it is clear that the present disclosure encompasses a rib having contact at mouth M or having sidewalls that are spaced apart at M.

For the embodiment of rib 16 a shown in FIG. 5A, the angle α at traverse point 54 a at radially inner wall 44 a and the angle β at traverse point 56 a at radially outer wall 48 a may be determined as described above for angle α and angle β for the embodiment shown in FIG. 5. The inclination of the area of rib 16 a may also be determined by a line drawn through mouth M, which is at the narrowest point between opposing sides of rib 16 a, such as opposing walls 44 a and 48 a. A point P may be defined on the line that is equidistant from the opposing sidewalls. The area within rib 16 a below the line across mouth M defines the area of rib 16 b for this purpose. The line R is drawn through point P such that it divides the rib area into equal halves. Line R defines the angle ρ of the rib area, measured from the vertical X in the same orientation as with inclination angle α.

FIG. 5B illustrates a third embodiment can end 10 b having a peripheral curl 12 b, a wall, such as chuck wall 14 b, a rib 16 b, a panel wall 18 b, and a center panel 20 b. Peripheral curl 12 b, wall 14 b, and center panel 20 b are generally the same as the components described for can end 10 of FIG. 5. Rib 16 b includes a rib inner wall 44 b that is the same as inner wall 44 of FIG. 5. Rib 16 b also includes a rib base 46 b, a rib outer wall 48 b, and a transition 50 b. Opposing rib walls 44 b and 48 b are approximately straight, or include approximately straight portions, that are approximately parallel. Panel wall 18 b extends radially inwardly into the structure of rib 16 b such that rib inner wall 44 b is formed as a lower portion of panel wall 18 b. Rib 16 b extends axially inwardly (that is downwardly as oriented in FIG. 5B) and generally radially outwardly from a curved transition 50 b, which extends from chuck wall 14 b.

For the embodiment of rib 16 b shown in FIG. 5B, the angle α of radially inner wall 44 b and the angle β of radially outer wall 48 b may be measured directly on the walls relative to axial vertical line X. The inclination of the area of rib 16 b may be determined by a line drawn through across the axially outer (that is, upper in the orientation of FIG. 5B) ends of the straight sidewall portions of sidewalls 44 and 48, that bisects the area with rib 16. A point P may be defined by drawing a line across the upper ends of the straight walls perpendicular to the walls such that point P is equidistant from the opposing sidewalls. The area within rib 16 b below the line across the sidewalls defines the area of rib 16 b for this purpose. The line R is drawn through point P such that it divides the rib area into equal halves. Line R defines the angle ρ of the rib area, measured from the vertical X in the same orientation as with inclination angle α.

FIG. 5C illustrates a fourth embodiment can end 10 c having a peripheral curl 12 c, a wall, such as chuck wall 14 c, a rib 16 c, a panel wall 18 c, and a center panel 20 c. Peripheral curl 12 c, wall 14 c, and center panel 20 c are generally the same as the components described for can end 10 of FIG. 5. Rib 16 c includes a rib inner wall 44 c that is the same as inner wall 44 of FIG. 5. Rib 16 c also includes a rib base 46 c and a transition 50 c. Opposing rib wall 44 c and transition 50 c preferably are convex and upwardly and mutually outwardly diverging. In this regard, transition 50 c extends is a convex curved wall that extends from the lower portion of wall 14 c to traverse point 56 c. Alternatively, wall 44 c and transition 50 c may be approximately straight, or may include approximately straight portions, that diverge upwardly. Panel wall 18 c extends radially inwardly into the structure of rib 16 c such that rib inner wall 44 c is formed as a lower portion of panel wall 18 b. Rib 16 c extends axially inwardly (that is downwardly as oriented in FIG. 5B) and generally radially outwardly from a curved transition 50C, which extends from chuck wall 14 c.

For the embodiment of rib 16 c shown in FIG. 5C, the angle α at radially inner wall 44 c and the angle β at radially outer wall transition 50 c may be determined as described above for angle α and angle β for the embodiment shown in FIG. 5. The inclination of the area of rib 16 a may be determined by a line R that divides the area of rib 16 into equal parts. To define line R, a line CP may be extended from center panel 20 c or plane defined by the center panel 20 c through the radially outer wall of the end, such as at transition 50 c. A midpoint P is defined on line CP and is equidistant from the radially outer end of center panel 20 c (that is, at the juncture between center panel 20 c and panel wall 18 c) and the radially outer wall of the end, such as at transition 50 c. The area within rib 16 a below line CP defines the area of rib 16 b for this purpose. The line R is drawn through point P such that it divides the rib area into equal halves. Line R defines the angle ρ of the rib area, measured from the vertical X in the same orientation as with inclination angle α in the other figures.

FIG. 5D illustrates a fifth embodiment can end 10 d having a peripheral curl 12 d, a wall, such as chuck wall 14 d, a rib 16 d, a panel wall 18 d, and a center panel 20 d. Peripheral curl 12 d, wall 14 d, and center panel 20 d are generally the same as the components described for can end 10 of FIG. 5. Inner end 34 d of panel wall 18 d includes a junction having a tight radius, from which a straight or approximately straight panel wall body 36 d extends axially inwardly and radially outwardly.

Rib 16 d includes a rib inner wall 44 d, a rib base 46 d, a rib outer wall 48 d, and a transition 50 a. The structure of rib 16 d, such as walls 44 d and 48 d, and/or inner wall 44 d and transition 50 d, preferably converge to form an enlarged mouth M (that is, enlarged relative to the mouth of the embodiment of FIG. 5), which can be defined as the narrowest portion of rib 16 d outside of rib base 46 d. Rib 16 d extends downwardly and generally radially outwardly from a curved transition 50, which extends from chuck wall 14 a.

For the embodiment of rib 16 d shown in FIG. 5D, the angle α at radially inner wall 44 d may be measured directly from the inclination of the wall relative to vertical in the orientation of FIG. 5B. The angle β at radially outer wall 48 d may be determined at traverse point 56 d as described above for angle β for the embodiment shown in FIG. 5. The inclination of the area of rib 16 d may be determined by a line drawn through across mouth M, which is at the narrowest point between opposing sides of rib 16 d, such as opposing walls 44 d and 48 a. A point P may be defined as equidistant from the opposing sidewalls at mouth M. The area within rib 16 d below the line across mouth M defines the area of rib 16 d for this purpose. The line R is drawn through point P such that it divides the rib area into equal halves. Line R defines the angle ρ of the rib area, measured from the vertical X in the same orientation as with inclination angle α.

In each of the embodiments shown in FIGS. 5A, 5B, 5C, and 5D, the angle α may be approximately 135 degrees. The angle α is preferably less than 180 degrees, more preferably no more than 150 degrees. Further, angle α preferably is more than 95 degrees, and more preferably more 105 degrees, and more preferably more than 115 degrees. The angle β may approximately 90 degrees, and in general is preferably more than 45 degrees, more preferably more than 60 degrees. The rib area angle ρ is preferably less than 180 degrees, more preferably no more than 150 degrees. Further, rib area angle ρ is preferably is more than 95 degrees, preferably more than 105 degrees and more preferably more than 115 degrees.

Referring FIGS. 5, 5A, 5B, 5C, and 5D to illustrate another aspect of the structure, an axially innermost point 52 (that is, the lowest most point shown in the figures) of rib 16 is located radially outside of the axially innermost end of wall 14. In other words, the diameter defined by rotating point 52 about a center vertical axis is greater than the diameter defined by the rotation about the center vertical axis of the point at which transition 50 meets and wall 14. As shown in FIG. 5A, the axially innermost point 52 a may be approximately vertically in-line with the lower end 53 a of wall 14 b such that the diameter D-52 a defined by point 52 a is approximately equal to the diameter D-53 a defined by the point at which transition 50 b yields to wall 14 b. Further, as shown in the Figures, curved transition 50 a defines a radially inner edge 53 a of the chuck wall structure such that radially inner edge 50 e of the chuck wall overhangs the radially outer edge 16 e of the rib 16.

As seen in plan view in FIG. 3, the radially inner edge 50 e presents an aperture of a certain diameter d1. The rib 16, together with the panel wall 18 and center panel 20, for the purpose of explaining the function of the end 10, provide a unitary structure having an outer diameter d2. The structures described herein, such as the embodiments of the panel wall and rib, provide some advantages.

First, the structure may provide for a taut center panel that, for example, is not floppy and may be under tensile stress. The taut center panel enhances the ability of the end to resist pressure that could result in the tab rising above the seam. The taut center panel in general may provide resistance to doming (that is, deformation from internal can pressure that tends to deform the center panel from flat to a dome shape). Further, the annular strengthening rib of the invention is in turn prevented from rising upwards by the chuck wall, whereas the bead of a conventional can end is able to roll upwards.

Second, the structure may resist internal pressure that would cause the seamed end permanently to reverse from a concave shape to a convex shape. In this regard the rib may increase the rigidity of the end as the pressure increases. Further, the rib is prevented from rising upwards by the chuck wall and is, at least initially upon encountering high pressure, resists vertical unrolling. The rib 16, together with the panel wall 18 and center panel 18, may be considered to present a pseudo-pressure vessel structure, (having the outer diameter d2.) In simple terms, it can thus be seen that, when the can end is attached to a can body and the can is pressurized, the internal pressure will tend to push the pseudo-pressure vessel structure in the axially outward direction, but that this structure is of too large a diameter to fit through the hole presented by the radially inner edge 50 e of the chuck wall structure at least in part because d2 is greater than d1. The center panel structure is thus too big to pass axially outwardly through the aperture provided by the chuck wall structure.

Third, the structure may provide improved leaking performance upon failure. The failure mode resists the formation of local creases.

The present invention is not limited to structures that exhibit all or any of the above advantages, and the present invention is not intended to be limited to any particular function or theory.

The structure and function of the ends described herein is an aspect of the present structure. FIG. 6 is a schematic, enlarged cross-sectional view of the can end 10 after it has been double-seamed onto the axial end of a can body, in order to demonstrate the failure mode of the can end 10 when the pressure difference between the inside and the outside of the can is increased, with a higher internal pressure than external pressure. Can end 10 exhibits a progressive failure mode (and at a higher pressure, for a given thickness of the can end material). The reasons for this are believed to be as follows.

The convex curved axially outer side surface of the panel wall 18 and the convex curved outer side surface of the curved transition 50 oppose each other at the mouth m of rib 16. This description is directed to an embodiment in which mouth m is open to the outer side of the can end 10, rather than for the opposed sides 20, 50 of the mouth m being into contact, in an pressurized state and under normal pressure conditions after being seamed onto a can, thereby enabling the concave groove formed by the rib to be cleaned and sterilised, and also prevents any surface treatments or coatings on the outer surface from being damaged, although it is not considered to be essential, and the present invention is intended also to encompass examples where the mouth m is formed with the opposed panel wall 20 and curved transition 50 in contact, as explained morefully elsewhere.

As shown in FIG. 6, when the internal pressure of the can to which the can end 10 has been double-seamed is sufficiently increased, then the can end 10 will deflect under the influence of the pressure difference. This deflection acts to push the domed central panel region including the center panel 18 and the sloped panel wall 20 in the axially outward direction. At the same time, the chuck wall 14 acts like a lever, and bends so as to deflect axially outwardly at the radially inside edge 50 e of the chuck wall structure.

This movement forces the pseudo-pressure vessel of the center panel 18 and sloping peripheral edge 20 into the opening defined by the radially inner edge 50 e of the chuck wall structure, essentially plugging the hole. This may cause the two opposed walls of rib 16, such as sides 20 and 50, to come into contact (if they were not already) and to cam against one another. This kissing of one surface against the other is shown at the point indicated by M in FIG. 6B, where the mouth M closes.

In some embodiments, the inventors believe that this causes the touching sides 20 and 50 to roll and slide against each other, which diminishes the likelihood of any defect occurring at a single annular position. The result is that, with further deflection of the can end 10 axially outwardly, the center panel 18 and the domed panel wall 18 eventually force their way through the aperture defined by the radially inner edge 50 e of the chuck wall structure, and that in doing so the rib portion 16 and the curved transition portion 50 will tend to eventually be uniformly and gradually unrolled as the pressure difference increases, without failing at a single point of weakness.

During this process the chuck wall 14 is also gradually deflected outwardly in a progressive manner. At the same time, the angle of the chuck wall 14 serves to transmit compression forces radially outwardly, resisted by the folded rings of can end and can body material making up the double seam. This assists in maintaining the integrity of the double seam until after the can end 10 has actually “flipped” inside out.

The further effect of the domed center panel structure 18, 20 coming into contact with the inner peripheral edge 50 e of the chuck wall structure is that the chuck wall 14 acts to resist axially outward movement of the center panel 18, and so further acts to inhibit the occurrence of tab-above-seam, where an opening tab on the center panel extends axially beyond the plane of the axially outermost edge of the seam.

The above description of the failure mode may also apply to the embodiments 10 a, 10 b, 10 c, and 10 d shown in FIGS. 5A through 5D if upon failure, the opposing sidewalls 44 and 48 collapse to form a teardrop structure in which the opposing sidewall are in contact at the axially outer end (that is, the upper end as oriented in the figures) and are spaced apart at the axially inner end near base 46 (omitting letter designations for clarity). Further, the present invention does not require that opposing sidewalls come into contact during failure, but rather encompasses a failure mode in which the walls remain spaced apart about a mouth.

Referring to FIG. 5C to illustrate another failure mode, the present invention encompasses a failure mode in which opposing sidewalls 44 c and 44 c collapse together. Thus, rather than forming a teardrop shape having the opposing walls at an upper end are in contact or spaced closely apart compared with the teardrop's midsection and/or base, the opposing walls 44 c and 44 c may move together yet remain outwardly diverging until the center panel and panel wall combination can evert into a convex shape.

Further, the deflection and failure mode shown in FIGS. 6 and 6A can be contrasted with that of two similar, alternative embodiments of the present invention, as shown in FIGS. 6B and 6C and in FIGS. 6D and 6E.

As seen in image (a) of FIG. 6C, this can end is initially formed with a closed mouth m′. As would be expected, this very closely mirrors the behaviour of the can end 10 of FIGS. 6 and 6A, with the chuck wall 14 resisting outward movement of the center panel structure 18, 20, and maintaining the integrity of the can end until a substantial degree of doming of the center panel 18 has occurred (see FIGS. 6 and 6B, and image (c) in FIGS. 6A and 6C), before the can end flips inside out.

As seen in FIGS. 6D and 6E, a further embodiment is illustrated in which the mouth m is initially formed to be open, and the can end is constructed in such a way that the mouth m remains open, through to the stage of flipping inside out, without the opposed sides of the mouth coming into contact. It will be appreciated from comparing FIG. 6D with FIGS. 6 and 6B that the center panel 18 in this third embodiment does not benefit from the restraining effect of the chuck wall 14 holding back the center panel structure 18, 20 by mutual contact. As such, a somewhat smaller degree of doming of the center panel 18 can be accommodated (see image (c) of FIG. 6E), as compared with the two other embodiments (see image (c) of FIGS. 6A and 6C), before the can end flips inside out.

It will be understood that the can end 10 shown in FIGS. 2 to 5 is in the condition following initial forming of the can end from a circular blank, and that further processing steps may be performed, such as adding reinforcing structures, scoring an aperture and attaching a tab to the center panel, or curling the peripheral cover hook to the desired shape for seaming onto the end of a can body. Similarly, a lining may be added to the can end to create a seal when it is seamed onto a can body.

With reference to FIGS. 7 to 12, tooling will be described which is adapted for forming the embodiment of the can end shown in FIGS. 2 to 6. FIGS. 7 to 12 all show cross-sectional views of the tooling and a circular blank 5 at various stages of being formed into the can end 10 in a plane through the tooling and can end that includes the central axis X of the can end 10, which is also the central axis of the blank 5 and a common central axis of the tooling.

FIG. 7 shows an enlarged cross-sectional view of the tooling at the end of a forming step for manufacturing the can end. The tooling includes inner tools for forming the inner side surface of the can end and outer tools for forming the outer side surface of the can end. The inner tools are arranged to be positioned on the axially inner side of a blank corresponding to the inner side of the can end, and the outer tools are arranged to be positioned on the opposite, axially outer side of the blank corresponding to the outer side of the can end.

The inner tooling includes an inner center panel tool 60 and an inner wall tool 70. The inner wall tool 70, as shown, concentrically surrounds and is substantially adjacent to the inner center panel tool 60, such that a radially outer wall 68 of the inner center panel tool 60 is adjacent a radially inner wall 72 of the inner wall tool 70. As will be discussed in more detail below, the radially inner wall 72 of the inner wall tool 70 beneficially cooperates with features of the inner center panel tool 60 in the forming of a blank 5 into a can end 10.

The outer tooling includes an outer center panel tool 80, an outer chuck wall tool 90 and an outer seam tool 100. The outer tools are concentrically arranged, with the outer chuck wall tool 90 surrounding and substantially adjacent to the outer center panel tool 80, such that a radially outer wall 86 of the outer center panel tool 80 is adjacent a radially inner wall 94 of the outer chuck wall tool 90, and with the outer seam tool 100 surrounding and substantially adjacent to the outer chuck wall tool 90, such that a radially outer wall 96 of the outer seam tool 100 is adjacent a radially inner wall 104 of the outer seam tool 100.

The inner tools and outer tools are also arranged concentrically with respect to one another, about a central axis corresponding to the central axis X of a can end which the tooling is for forming (as well as that of the circular blank 5 to be formed into the can end 10 by the tooling).

The tools are arranged such that the inner tools can move axially relative to one another, and so that the outer tools can move axially relative to one another. Similarly, the inner tools are able to move axially relative to the outer tools. Movement of the outer tools relative to the inner tools is restricted by the inner and outer tools being opposed to one another. In particular, the inner center panel tool 60 is opposed to the outer center panel tool 80, whilst the inner wall tool 70 is opposed to the outer chuck wall tool 90 and the outer seam tool 100. Outer chuck wall tool 90 and outer seam tool 100 are thus also considered as being outer wall tools.

As shown in FIG. 8, the outer center panel tool 80 has an outer diameter at its radially outer wall 86 that is less than the inner diameter at the radially inner wall 72 of the inner wall tool 70, and, similarly, less than the outer diameter at the radially outer wall 68 of the inner center panel tool 60. As such, the outer center panel tool 80 may move axially to become at least partially disposed within said inner wall tool 70, leaving an annular gap G between the radially inner wall 72 of the inner wall tool 70 and the radially outer wall 86 of the outer center panel tool 80.

A radially inner portion of the outer chuck wall tool 90 is arranged to extend across, and thereby form a radially outer boundary of, the annular gap G on the outer side of the tooling, whilst a radially outer peripheral portion of the inner center panel tool 60 is arranged to extend across, and thereby form a radially inner boundary of, the gap G on the inner side of the tooling, these portions of the two tools thus also being opposed to one another in this region. In operation of the tooling, the opposed inner and outer center panel tools 60 and 80 move together relative to the opposed inner and outer wall tools 70, 90 and 100, in order to effect axial compression of the portion 7 of the blank 5 between the opposed radially inner portion of the outer chuck wall tool 90 and the radially outer peripheral portion of the inner center panel tool 60 opposed thereto.

In particular, the tooling is configured to form the panel wall 20, rib 16 and curved transition 50 of can end 10 by axially compressing an axially extending portion 7 of a blank 5 which extends across the annular gap G between the upper and lower tools.

A component of the tooling is the inner center panel tool 60. The inner center panel tool 60 has an axially outwardly facing surface that is configured to promote the formation of the panel wall and annular bead structures of the can end 10. The external shape of the inner center panel tool 60 substantially corresponds to the shape of the axially inwardly facing portions of center panel 18, the panel wall 20 and the rib 16 of the inner surface of the can end 10.

In the example here, inner center panel tool 60 has a central panel region 62 that is substantially flat. A sloping peripheral wall 64 extends radially outwardly and axially inwardly from the edge of the central panel region 62. In the cross-sectional plane including the central axis of the tooling, the radially outer edge of the sloping peripheral wall 64 terminates in an axially outward peak 67, so as to form a concave annular recess 66 facing in the axially outward direction. The concave annular recess 66 corresponds with, and is arranged to promote formation of, the rib 16. The concave annular recess, in particular, faces or opens into the gap G formed between the outer center panel tool 80 and the inner wall tool 70.

A feature of the inner center panel tool 60 is that the central panel region 62 smoothly blends at its outer periphery with the sloping peripheral wall 64. The sloping peripheral wall 64 is shaped so as to curve gradually axially inwardly away from the central panel 62 region in the radially outward direction. In the example shown, the curved sloping peripheral wall blends smoothly at its radially inner end with the central panel region 62 and at its radially outer end into the concave annular recess 66.

The gradual curvature of the sloping peripheral wall, away from the central panel region, serves to encourage the axially extending portion 7 of a blank 5 which is axially compressed against the inner center panel tool 60 to roll out ontothe sloping peripheral surface 64 from the central panel region 62 in a radially outward direction, so that the inner surface of the blank will adopt the shape of the axially outward surface of the inner center panel tool 60. In the example shown, the sloping peripheral wall 64 has a substantially constant curvature, although it is contemplated that the sloping peripheral wall 64 may include straight sections which are nevertheless sloped axially inwardly and radially outwardly.

The concave annular recess 66 is also shown as being of substantially constant curvature, and having a radius of curvature which is substantially smaller than the radius of curvature of the convex portion of sloping peripheral wall 64. This concave annular recess 66 allows part of the intermediate annular portion 7 of a blank 5 which is being axially compressed to within the recess during the axial compression process, to produce the tightly rolled or tightly curved bead portion of rib 16. This rolling or curving of the annular bead also serves to draw the blank material in the central panel region 6 radially outwardly, so as to bring the central panel region 6 into tension as the blank 5 being formed is pressed against the inner center panel tool 60 and the rib 16 is rolled or deformed tight in the annular recess 66.

The lower center panel tool 60 is arranged to cooperate with the radially inner wall 72 of the inner wall tool 70. As can be seen in FIG. 7, the axially outward annular peak 7 at the peripheral edge of the sloping peripheral wall 64 provides a relatively smooth transition between the concave annular recess 66 and the radially inner wall 72 of the inner wall tool 70. The radially inner wall 72 of the lower wall tool 70 thus acts to inhibit radially outward deflection of the axially extending portion 7 of the blank 5 as it is compressed in the annular gap G. This in turn helps to urge the material to form into a roll in the annular recess 66, and to cause the material to become more tightly rolled or curved as the axial compression proceeds further.

The sloping peripheral wall 64 and the concave annular recess 66 of the inner center panel tool, together with the radially inner wall 72 of the inner wall tool 70, define an annular recess R. Annular recess R is concave, facing in the axially outward direction, and is recessed relative to the substantially flat central panel region 62 of the inner center panel tool 60. Annular recess R substantially opposes the annular gap G between the outer center panel tool 80 and the inner wall tool 70.

The outer center panel tool 80 has an outer diameter at the radially outer wall 86 which is larger than the diameter of the flat central panel region 62 of the inner center panel tool 60. In the example shown, a central panel region 82 of the outer center panel tool 80 is also slightly larger than the central panel region 62 of the inner center panel tool 60. The outer center panel tool 80 also exhibits a sloping peripheral wall 84, extending from the central panel region 82 to the radially outer wall 86 in the axially- and radially-outward direction. The sloping peripheral wall 84 is preferably curved to extend gradually axially outwardly from the central panel region 84 in the radially outward direction. As shown, the sloping peripheral wall 84 may be continuously curved so as to blend at one end with the central panel region 82 and at the other end with the radially outer wall 86. The sloping peripheral wall 84 may have a constant radius of curvature.

As can be seen in FIG. 8, the sloping peripheral wall 84 has a function in allowing the circular blank 5 to be axially drawn to form an intermediate annular portion 7 which extends axially- and radially-outwardly from the center panel region 6 of the blank 5. It is this axially drawn, intermediate annular portion 7 which is subsequently axially compressed to form the panel wall 20, rib 16 and curved transition 50. In the axial drawing process, the curvature of the sloping peripheral wall 84 allows the circular blank to be drawn around the outer center panel tool 80 whilst permitting material flow from the center panel region 6 radially outwardly without having to pass around a sharp corner that could inhibit material flow and result in drawing defects.

By having a diameter larger than that of the central panel region 62 of the inner center panel tool 60, the outer center panel tool 80 also causes the drawn, axially extending, intermediate annular portion 7 to be formed with a radially-outward curve that acts as a preliminary buckle near to the peripheral edge of the center panel region 6. Consequently, when the intermediate annular portion is subsequently axially compressed against the inner center panel tool 60, it will tend to buckle radially outwardly from the point of the preliminary buckle formed by the sloping peripheral wall 84 of the outer center panel tool 80. This promotes the blank material in the radially innermost portion 7 a of the intermediate annular portion 7 to roll radially outwardly along the outer surface of the inner center panel tool 60 when the blank is first axially compressed, and so for that radially innermost portion 7 a to adopt the shape of the sloping peripheral wall 64.

As mentioned above, the inner wall tool 70 opposes the outer wall tools, including the outer chuck wall tool 90 and the outer seam tool 100.

In order to form a sloping chuck wall 14, the outer chuck wall tool 90 includes an axially inwardly facing chuck wall surface 92 which is angled axially- and radially-outwardly. The inner wall tool 70 similarly includes an axially outwardly facing surface including a radially inner portion formed as a chuck wall surface 74 and angled axially- and radially-outwardly in the same way as the outer chuck wall tool. The chuck wall surface 74 of the inner wall tool 70 opposes the chuck wall surface 92 of the outer chuck wall tool 90, and these surfaces clamp part of an outermost portion 8 of the circular blank 5 to form the chuck wall 14 during drawing and reforming of the blank 5.

In a similar manner, in order to form a seaming panel 26, the outer seam tool 100 includes an axially-inwardly facing seaming panel surface 102 which extends radially-outwardly and is slightly concavely curved facing in the axially inward direction. The axially outwardly facing surface of the inner wall tool 70 similarly includes a radially outer portion formed as a seaming pane surface 76 which extends radially-outwardly in the same way as the seaming panel surface 102 of the outer seam tool 100, and which is slightly convexly curved in the axially outward direction, to match the concave curvature of the seaming panel wall 102 of the outer seam tool 100. The seaming panel surface 76 of the inner wall tool 70 opposes the seaming panel surface 102 of the outer seam tool 100, and these surfaces clamp part a radially outer portion of the outermost portion 8 of the circular blank 5 to form the seaming panel 26 during drawing and reforming of the blank 5.

It will be appreciated that the tooling is configured to form the panel wall 20, rib 16, and the curved connection portion 50 with only a single axial movement of the opposed inner and outer wall tools 70, 90 and 100 in an axially inward direction relative to the opposed inner and outer center panel tools 60 and 80.

FIGS. 9 to 11 show cross-sectional views of the tooling at several different axial positions during the forming of can end 10 by axial compression of the blank 5. FIGS. 9A to 11A show enlarged views of the circled parts, respectively, of FIGS. 9 to 11.

The circular blank may be considered as nominally including three regions, a center panel region 6 corresponding to the central panel region 62 of the inner center panel tool, an intermediate annular portion 7 which extends radially outwardly from the peripheral edge of the center panel region 6 across the annular gap G, and an outermost peripheral portion 8, being the portion of the blank 5 extending radially outwardly of the radially inner edge 72 of the inner wall tool 70. These regions are thus defined with respect to the tooling, and it will be appreciated that the particular material of the blank 5 in each region may change during the processing of the blank, due to material flow from one region to the next as the blank 5 is drawn and reformed.

In FIG. 9, the opposed inner and outer wall tools 70, 90 and 100 clamp an outermost peripheral portion 8 of the blank 5, whilst opposed inner and outer center panel tools 60 and 80 clamp a center panel region 6 of the blank 5. Intermediate annular portion 7 of the blank 5 is unclamped, and extends across the annular gap G. In the view shown in FIG. 9, the opposed inner and outer wall tools 70, 90 and 100 have been moved axially outwardly relative to the opposed inner and outer center panel tools 60 and 80, so as to axially draw the blank 5 to form axially extending intermediate annular portion 7, which extends radially- and axially-outwardly from the center panel region 5 across the annular gap G.

In FIG. 10, the opposed inner and outer wall tools 70, 90 and 100 have been moved axially inwardly relative to the opposed inner and outer center panel tools 60 and 80 in order to reform the intermediate annular portion 7 by axially compressing it. The intermediate portion has buckled radially outwardly from the preliminary inward buckle formed by the sloping peripheral wall 84 of the outer center panel tool 80, and the inner portion 7 a of the intermediate annular portion 7 has rolled around the sloping peripheral wall to adopt the shape of the peripheral annular wall, including the concave annular recess 66. The radially inner portion 7 a thus lies in the annular recess R opposed to the annular gap G.

Reforming the intermediate portion 7 a in this way brings the material of the blank in the center panel region and/or in the panel wall into tension, as it is effectively “stretched” over the peripheral forming surface of the inner center panel tool 60. Accompanying material flow across the center panel region 6, as the blank is axially compressed against the inner center panel tool 60, is shown schematically with arrows in FIG. 12.

The radially outer end of the radially inner portion 7 a is pressed against and constrained by the radially inner wall 72 of the inner wall tool 70. The remaining portion 7 b of the intermediate annular portion 7 is axially compressed and has bent radially inwardly due to the bending stresses created in the material to form a second preliminary buckle. The upper part of the second preliminary buckle comes into contact with, and is constrained and supported by the axially inwardly facing chuck wall surface 92 of the outer chuck wall tool 90.

In FIG. 11, the opposed inner and outer wall tools 70, 90 and 100 have been moved further axially inwardly relative to the opposed inner and outer center panel tools 60 and 80 in order to further reform the intermediate annular portion 7 by further axially compressing it. The remaining portion 7 b of the intermediate annular portion 7 further curves and deforms radially inwardly from the radially inward curve. The upper part of the remaining portion 7 b has rolled against the portion of the chuck wall surface 92 of the outer chuck wall tool 90 which extends across the annular gap G to conform to the shape of the chuck wall surface 92, thus forming a radially inner portion of the chuck wall 14.

The further axial compression has caused the radially inward curve in the remaining portion 7 b to tighten, forming the curved transition 50. As the curved transition is formed and pressed axially inwardly by the chuck wall surface 92, the radially inward curve tightens and forms the curved transition, and at the same time forces the blank material into the concave annular recess 66 of the inner center panel tool 60 to cause it to roll up tightly to form the rib 16. This tightening of the bead causes it to roll in the concave annular recess 66, drawing the blank material tight and bringing the center panel region 6 into tension.

The tightening of the rib 16 by it being rolled in the concave annular recess 66, and the accompanying material flow across the center panel region 6, is shown schematically with arrows in FIG. 12.

FIGS. 13 to 17 again show enlarged cross-sectional views of the tooling at several different axial positions during the forming of can end 10 by axial compression of the blank 5. A method of forming the can end 10 will be described with reference to these Figures.

A preliminary step in the method involves axially drawing the circular blank 5 by drawing an outermost peripheral portion 8 of the blank 5 in an axially outward direction relative to a center panel region 6 of the blank, to create an intermediate annular portion 7 extending radially- and axially-outwardly from the peripheral edge of the center panel region 6. The drawn intermediate annular portion 7, as shown in FIG. 13, extends predominantly axially outwardly between the center panel region 6 and the outermost peripheral portion 8, which are respectively clamped to facilitate the axial drawing. The axial drawing process is arranged so as to impart a preliminary radially outward curve into the intermediate annular portion 7 substantially adjacent to the peripheral edge of the center panel region 6.

As can be seen in FIG. 13, when the drawn intermediate annular portion 7 is subsequently axially compressed, the compressive forces will be transmitted along the substantially straight-walled section of the intermediate annular portion 7, and will tend to push the radially outward curve to deform it axially inwardly onto the sloping peripheral wall 64 which is part of the axially outer forming surface of inner center panel tool 60. This will tend to cause the radially innermost part 7 a of the intermediate annular portion to roll radially outwardly onto the sloping peripheral wall 64 from the peripheral edge of the center panel region 6. At the same time, compressive forces acting at the opposite end of the intermediate annular portion 7 are resisted by the outermost peripheral portion 8 being clamped, and in particular by the radially- and axially-inward slope of a clamped chuck wall portion of the outermost peripheral portion 8 being less susceptible to deformation than the radially outward curve near the center panel region 6.

FIGS. 14 to 17 show progressive stages of the axial compression process by which the drawn intermediate annular portion 7 is then reformed.

As seen in FIG. 14, when the outermost peripheral portion 8 is moved axially inwardly relative to the center panel region 6, the radially inner portion 7 a of the intermediate annular portion 7 rolls radially outwardly and axially inwardly onto the forming surface of the inner center panel tool 60 and substantially adopts the shape of the sloping peripheral wall 64, including the concave annular recess 66.

As further radially outward rolling of the radially outward curve is constrained by the radially inner wall 72 of the inner wall tool 70, and also as a result of the shape of the concave annular recess 66 which terminates in the axially outward peak 67 at its radially outer edge, the intermediate annular portion 7 cannot be rolled further radially outwardly. Adopting the shape of the concave annular recess 66, bending moments are induced in the radially inner portion 7 a of the intermediate annular portion 7, which in turn form a radially inward curve in the remaining portion 7 b of the intermediate annular portion 7. This causes the remaining portion 7 b, which otherwise extends predominantly axially, to bow radially inwardly at around the center, in the axial direction, of the remaining portion 7 b.

With reference to FIGS. 15 and 16, further axial compression, by further moving the outermost peripheral portion 8 axially inwardly relative to the center panel region 6, the initial radially inward curve progressively collapses further radially inwardly at the axial center of the remaining portion 7 b. The upper end of the remaining portion 7 b then rolls radially outwardly onto, and is pressed axially inwardly by, a radially- and axially-inwardly sloped forming surface, here provided by the chuck wall surface 92 of the outer chuck wall tool 90 extending across the annular gap G.

At the same time, the axially inward deformation of the radially inward curve causes the lower end of remaining portion 7 b to force the curved portion of the radially inner portion 7 a of the intermediate annular portion 7 which has been formed in the concave annular recess 66 to roll up. This causes the annular bead 16 to be formed as a tightly rolled, continuously curved bead. The bead may exhibit a substantially constant curvature defined by the radius of curvature of the concave annular recess 66.

The further axial compression, together with the rolling of the material in the concave annular recess 66, also causes the radially inward curve to tighten into a curve with reduced radius of curvature, forming the curved transition 50.

As shown in FIG. 17, final axial compression by moving the outermost peripheral portion 8 axially inwardly relative to the center panel region 6 tightens the rib 16 and curved transition 50 to their final radii of curvature, without axially collapsing these bead structures. The axial compression is preferably terminated at a point before the radially inward curve comes into contact with the radially inner portion 7 a of the intermediate annular portion 7, so that an open mouth m is formed between the curved transition 50 and the panel wall 20 of the formed can end 10. Alternatively, the axial compression may continue until these surfaces are brought into contact, with the mouth m closed.

As will be apparent, all of the axial compression illustrated, from the position in FIG. 14 to that in FIG. 17, is achieved by a single axial motion of moving the outermost peripheral portion 8 of the blank 5 axially inwardly relative to the center panel region 6, so as to reform the axially drawn intermediate annular portion 7 in a single operation.

It is also to be noted that, as a reflow process is used to form the rib 16 and the curved transition 50, these can be formed from a blank of relatively thin material to have very small inner radii, which would not be possible with conventional press tooling. In particular, where the inner radii of pressed components are very small, the tools used to form them cannot be removed without damaging the material of the blank or increasing the thickness of the blank to give it more strength. By contrast, the reflow method used in the method above allows a tightly rolled annular bead and adjacent curved transition to be formed from a thin blank without damage.

The can end 10 is formed upon completion of this operation, although as noted above further processing steps may be carried out on the can end.

Turning to FIG. 18, there is shown an enlarged view, similar to FIG. 4A, of the bead and chuck wall portion of another embodiment of a can end according to the present invention, where side walls defining the bead mouth are parallel.

Specifically, all features of the can end are the same as described above for the can end of FIGS. 2 to 5, except that the sides of the bead mouth do not converge, and straight-walled sections 40 and 49, respectively, connect the curved panel wall 20 and curved transition 50 to each end 44 and 48 of the bead wall 46.

Nevertheless, the center panel structure retains a substantially outwardly domed shape, and the bead 16 extends radially outwardly of the inner peripheral edge of the chuck wall structure.

FIG. 19 shows an enlarged view, similar to FIG. 4A, of the bead and chuck wall portion of a further embodiment of a can end according to the present invention, where the side walls defining the bead mouth diverge.

In this example, again, a straight walled section 40 is provided in the panel wall, between curved panel wall 20 and the inner end 44 of the bead wall 46. On the outer side of the bead 16, the outer end 48 of the bead wall 46 connects directly to the curved transition region 50 at a point of inflexion. The straight wall section 40 and the curved transition 50 are divergent from the bead 16 towards the outside of the can end.

At the same time, the center panel structure retains a substantially outwardly domed shape, and the bead 16 extends radially outwardly of the inner peripheral edge of the chuck wall structure.

FIG. 20 shows an enlarged view, also similar to FIG. 4A, of the bead and chuck wall portion of still another embodiment of a can end according to the present invention, where the panel wall includes a substantially straight section 40 between the center panel 18 and the bead 16. On the opposed side of the bead, the curved transition 50 and annular bead 16 are substantially the same as in the embodiment of FIGS. 2 to 5.

Once again, the center panel structure retains a substantially outwardly domed shape, and the bead 16 extends radially outwardly of the inner peripheral edge of the chuck wall structure. The embodiment of FIG. 20 is also likely to benefit from the straight panel wall section 40 and curved transition 50 coming into contact as the can end deflects under pressure, such that improved failure behaviour of the can end can be obtained.

Aspects of the present invention are described herein. But according to well established principles, the claims are intended to provide the scope of the invention and should receive their plain meaning. 

1. A can end for a can for pressurized contents, the can end being configured to be joined by a peripheral annular joining portion to one axial end of a can body of the can and having an outer side arranged to face outwardly from the can and an inner side arranged to face inwardly into the can, the can end comprising: a central panel; a panel wall annularly surrounding the central panel and extending axially inwardly and radially outwardly from the central panel; an annular chuck wall structure extending radially- and axially-inwardly from the joining portion; and an annular bead which is connected between a radially outer edge of the panel wall and a radially inner edge of the chuck wall structure and which is concave with respect to the outer side of the can end and extends at least partially radially outwardly with respect to the radially inner edge of the chuck wall structure, wherein wall portions adjacent inner and outer ends of the concave annular bead form a bead mouth that is open towards the outer side of the can end.
 2. The can end of claim 1, wherein said bead mouth is the point of closest approximation of the wall portions adjacent inner and outer ends of the concave annular bead.
 3. The can end of claim 1, wherein the annular bead exhibits a cross-sectional profile which, in a plane through the can end which includes a central axis of the can end, substantially inscribes a circle.
 4. The can end of claim 1, wherein the annular bead is open to the outer side in a direction radially inwardly and axially outwardly from the inscribed circle.
 5. The can end of claim 1, wherein, in a plane through the can end which includes a central axis of the can end, the adjacent wall portions forming the bead mouth are parallel or diverge from the inner and outer ends of the annular bead towards the outer side of the can end.
 6. A can end for a can for pressurized contents, the can end being configured to be joined by a peripheral annular joining portion to one axial end of a can body of the can and having an outer side arranged to face outwardly from the can and an inner side arranged to face inwardly into the can, the can end comprising: a central panel; a panel wall annularly surrounding the central panel and extending axially inwardly and radially outwardly from the central panel; an annular chuck wall structure extending radially- and axially-inwardly from the joining portion; and an annular bead which is connected between a radially outer edge of the panel wall and a radially inner edge of the chuck wall structure and which is concave with respect to the outer side of the can end and extends at least partially radially outwardly with respect to the radially inner edge of the chuck wall structure, wherein the annular bead exhibits a cross-sectional profile which, in a plane through the can end which includes a central axis of the can end, substantially inscribes a circle, and wherein wall portions adjacent inner and outer ends of the annular bead form a bead mouth that is disposed axially outwardly and radially inwardly of the inscribed circle.
 7. The can end according to claim 6, wherein said bead mouth is the point of closest approximation of the adjacent wall portions nearest to the center of said inscribed circle.
 8. The can end of claim 6, wherein the panel wall is convexly curved with respect to the can end outer side, wherein the chuck wall structure includes an annular chuck wall extending radially- and axially-inwardly, and the radially inner end of the annular chuck wall is connected to the annular bead via a portion which is convexly curved with respect to the can end outer side and which does not touch the outer side surface of the panel wall, and wherein the can end is configured such that, when the can end is joined to a can body and internal pressure in the can is increased so as to cause the can end to bulge outwardly, the convexly curved panel wall will kiss against the convexly curved portion at the radially inner end of the annular chuck wall.
 9. The can end of claim 6, wherein the annular bead exhibits a cross-sectional profile which, in a plane through the can end which includes a central axis of the can end, has a bead wall that is substantially continuously concavely curved through more than 180 degrees, and wherein said concave bead wall terminates at its outer end at an angle with respect to the central axis of the can end of not less than 45 degrees, said angle being measured in the cross-sectional plane from the central axis in the outward direction to the tangent to the panel wall at the radially outer end of the concave curvature in the direction of the bead wall moving from the central panel to the chuck wall.
 10. The can end according to claim 9, wherein the panel wall blends at its radially outer edge into the concave curvature of the annular bead, and wherein, in said plane through the can end, a tangent to the wall of the can end at the transition point between the convex panel wall and the concave annular bead, in a radially outward direction, is at an angle from the outer axial direction of not more than 150 degrees, measured in said plane.
 11. The can end according to claim 6, wherein the panel wall is convexly curved with respect to the outer side of the can end, and blends at its radially outer edge into the concave curvature of the annular bead, which maintains a substantially constant curvature through more than 180 degrees, and wherein, in a plane through the can end which includes a central axis of the can end, a tangent to the wall of the can end at the transition point between the convex panel wall and the concave annular bead, in a radially outward direction, is at an angle from the outer axial direction of not more than 150 degrees, measured in said plane.
 12. The can end according to claim 9, wherein the annular bead is substantially continuously curved through more than 225 degrees.
 13. The can end according to claim 9, wherein said angle of the tangent to the wall of the can end at the transition point from the axial outer direction is not more than 135 degrees.
 14. A can end for a can for pressurized contents, the can end being configured to be joined by a peripheral annular joining portion to one axial end of a can body of the can and having an outer side arranged to face outwardly from the can and an inner side arranged to face inwardly into the can, the can end comprising: a central panel; a panel wall annularly surrounding the central panel and extending axially inwardly and radially outwardly from the central panel; an annular chuck wall structure extending radially- and axially-inwardly from the joining portion; and an annular bead which is connected between a radially outer edge of the panel wall and a radially inner edge of the chuck wall structure and which is concave with respect to the outer side of the can end and extends at least partially radially outwardly with respect to the radially inner edge of the chuck wall structure, wherein said panel wall and said annular bead are integrally formed by reforming a blank by axially compressing it against an inner center panel tool that has an axially inwardly and radially outwardly sloped surface extending from a central panel region and is provided at its peripheral radially outer edge with a curved annular recess facing the outer side, said curved annular recess thereby forming said annular bead.
 15. A can end for a can for pressurized contents, the can end being configured to be joined by a peripheral annular joining portion to one axial end of a can body of the can and having an outer side arranged to face outwardly from the can and an inner side arranged to face inwardly into the can, the can end comprising: a central panel; a panel wall annularly surrounding the central panel and extending axially inwardly and radially outwardly from the central panel; an annular chuck wall structure extending radially- and axially-inwardly from the joining portion; and an annular bead which is connected between a radially outer edge of the panel wall and a radially inner edge of the chuck wall structure and which is concave with respect to the outer side of the can end and extends at least partially radially outwardly with respect to the radially inner edge of the chuck wall structure, wherein the material of the can end is not folded or in contact with itself between the radially outer edge of the panel wall and the radially inner edge of the chuck wall structure.
 16. A can end according claim 15, further comprising a cover, label, token, tab or other material provided in the annular bead.
 17. A method of manufacturing a can end comprising: reforming a blank by compressing an axially extending annular portion of the blank material that surrounds a central panel region of the blank to cause at least a radially inner portion of the annular portion to flow into and substantially adopt the shape of an annular recess provided on the opposite side of the central panel, in the axial direction, to the direction in which the annular portion initially axially extends; and further reforming the blank under axial compression with at least the central panel region of the blank under tension.
 18. The method of claim 17, wherein reforming the blank includes axially compressing the annular portion against an annular tool surface extending radially outwardly from the central panel region and curving axially away from the direction in which the annular portion of the blank initially axially extends and terminating in a concave annular recess that faces back towards the direction in which the annular portion initially axially extends, such that at least the radially innermost portion of the annular portion rolls radially outwardly around the annular tool surface from the radially outer edge of the central panel region to substantially adopt the shape of said annular tool surface.
 19. The method of claim 17, wherein the annular recess includes at the radially outer edge thereof an annular concave portion facing axially outwardly and configured to promote the formation of an axially outwardly concave and radially outwardly extending bead portion.
 20. The method of claim 17, wherein axially compressing the blank to cause at least the radially inner portion of the annular portion to flow into and substantially adopt the shape of the annular recess imparts a preliminary radially inward curve in a remaining portion of the annular portion that otherwise extends axially from the radially outer edge of the annular recess to an or the outermost peripheral portion of the blank that is held to facilitate said axial compression.
 21. The method of claim 20, wherein reforming the blank includes further axially compressing the blank to cause said preliminary radially inward curve in the remaining portion of the annular portion to further deform radially inwardly.
 22. The method of claim 21, wherein further axially compressing the blank includes supporting an axially outer side of the remaining portion of the annular portion by an outer chuck wall tool, so that the axial outer end of the radially inwardly curved remaining portion is at least partially formed into at least part of a chuck wall of the end can by said further axial compression.
 23. The method of claim 17, wherein all of the reforming and further reforming is performed by a single motion to progressively axially compress and reform the annular portion of the blank.
 24. A method of manufacturing a can end comprising: reforming a blank by compressing an axially extending annular portion of the blank material that surrounds a central panel region of the blank against an annular tool surface extending radially outwardly from the central panel region and curving axially away from the direction in which the annular portion of the blank initially axially extends and terminating in a concave annular recess that faces back towards the direction in which the annular portion initially axially extends, such that at least the radially innermost portion of the annular portion rolls radially outwardly around the annular tool surface from the radially outer edge of the central panel region to substantially adopt the shape of said annular tool surface.
 25. The method of claim 24, further including axially drawing the blank by drawing an outermost peripheral portion of the blank in an axially outward direction relative to the central panel region of the blank in order to draw an intermediate annular portion of the blank such that it extends radially- and axially-outwardly from the central panel region to the outermost peripheral portion as said axially extending annular portion.
 26. The method of claim 25, wherein axially drawing the blank introduces a preliminary radially outward curve into the annular portion of the blank in the vicinity of the central panel region of the blank.
 27. An inner center panel tool for pressing against the inner side of a blank in the manufacture of a can end to reform the blank against said tool, the tool comprising an axially outwardly facing central panel region and a sloped peripheral surface extending axially inwardly and radially outwardly from the central panel region and terminating at its radially outer peripheral edge in a concave annular recess facing in the axially outward direction.
 28. The tool of claim 27, wherein said sloped peripheral surface curves gradually axially inwardly away from the central panel region in the radially outward direction to form said slope as a domed convex annulus.
 29. The tool of claim 27, wherein said concave annular recess is concavely curved.
 30. Tooling for manufacturing a can end to be joined to one axial end of a can body of a can for pressurized contents, comprising: an inner center panel tool for forming the inner side of a can end corresponding to the inside of the can and arranged to be disposed concentrically within an inner wall tool so as to be substantially adjacent to a radially inside wall of the inner wall tool, wherein said inner center panel tool has a peripheral surface sloping axially inwardly in a radially outward direction from a central panel region of the inner center panel tool, such that said peripheral surface together with said inside wall of the inner wall tool defines an annular recess axially inwardly of the central panel region, and wherein said annular recess is configured to promote the formation of a radially outwardly extending bead in a can end during a reform process of axially compressing a blank against the inner center panel tool.
 31. The tooling of claim 30, wherein said peripheral surface is sloped relative to the axial direction across at least 25% of the radial width of said annular recess extending radially outwardly from said central panel region.
 32. The tooling of claim 30, wherein an axially outwardly facing concave annular recess is formed at the radially outer edge of the peripheral surface of the inner center panel tool, so as, together with the inside wall of the inner wall tool, to promote said formation of the radially outwardly extending bead during the reform process of axially compressing a blank against the inner center panel tool.
 33. The tooling of claim 30, wherein said peripheral surface is convexly curved gradually axially inwardly away from the central panel region in the radially outward direction to form said slope as a domed convex annulus.
 34. Tooling for manufacturing a can end to be double-seamed onto one axial end of a can body of a can, comprising: inner tools for forming the can end on a side corresponding to the inside of the can and arranged to be disposed on an axially inner side of outer tools for forming the can end on a side corresponding to the outside of the can, including: an inner center panel tool; an inner wall tool arranged concentrically surrounding and substantially adjacent to the inner center panel tool; an outer center panel tool opposed to the inner center panel tool; and at least one outer wall tool generally opposed to the inner wall tool and arranged concentrically surrounding and substantially adjacent to the outer center panel tool, wherein the opposed inner and outer wall tools are able to move axially relative to the opposed inner and outer center panel tools, wherein the outer center panel tool has a smaller outside diameter than the inside diameter of a radially inner wall of the inner wall tool, the outer center panel tool being disposable concentrically at least partially within the inner wall tool to leave an annular gap radially surrounding the outer center panel tool, and wherein the inner center panel tool includes a peripheral annular surface surrounding a central panel region of the inner center panel tool and extending axially inwardly in a radially outward direction from the central panel region, the peripheral annular surface, together with the radially inner wall of the inner wall tool, defining an annular recess extending axially inwardly from the central panel region of the inner center panel tool, said annular recess being substantially opposed to said annular gap.
 35. The tooling of claim 34, wherein the peripheral annular surface terminates at its radially outer end in an annular recess configured to promote the formation of a radially outwardly extending recess during a reform process of axially compressing a blank against the inner center panel tool.
 36. The tooling of claim 34, wherein the at least one outer wall tool includes a chuck wall tool arranged concentrically surrounding and substantially adjacent to the outer center panel tool and extending across the annular gap substantially opposed to the annular recess.
 37. The tooling of claim 36, wherein the chuck wall tool includes an axially inwardly facing annular surface opposed to the annular recess, said inwardly facing surface being sloped axially outwardly in the radially outward direction.
 38. A can end, the can end being configured to be joined by a peripheral annular joining portion to one axial end of a can body of the can and having an outer side arranged to face outwardly from the can and an inner side arranged to face inwardly into the can, the can end comprising: an annular structure which is concave with respect to the outer side of the can end and is connected to: a center panel structure radially inside the annular structure; and a chuck wall structure annularly surrounding the annular structure and extending axially- and radially-outwardly from the annular structure; and a cover, label, token or tab, or other material, provided at least partially within the concave annular structure.
 39. The can end of claim 38, wherein the can end is for a can for pressurized contents and is arranged such that, when the can end is joined to a can body and internal pressure in the can is increased, the can end will be deformed such that wall portions at each side of the annular structure close on the cover, label, token, tab or other material provided in the concave annular structure.
 40. The can end of claim 38, wherein the cover, label, token or tab substantially encloses an opening of the can end to maintain a sterile or hygienic condition on the enclosed outer side surface of the can.
 41. The can end of claim 38, wherein the cover, label, token or tab cooperates with or forms part of an opening and/or re-sealing feature of the can end.
 42. The can end of claim 38, wherein the cover, label, token, tab or other material is provided in the concave annular structure to provide reinforcement or to control the deflection and/or failure behaviour of the can end.
 43. A lightweight beverage can end comprising: a peripheral curl including a cover hook and a seaming panel; a wall extending inwardly from the curl an annular bead extending radially outwardly from a lower portion of the chuck wall (radially outwardly in this context does not mean that all of the bead is radially outward of the bottom of the wall, just generally outwardly); an center panel having an approximately flat central and a panel wall sloping downwardly at the periphery of the center panel and connected to the bead.
 44. The can end of claim 43 wherein the panel wall is curved.
 45. The can end of claim 43 wherein the bead includes a bead outer wall that extends radially outwardly from the lower portion of the wall.
 46. The can end of claim 44 wherein the bead outer wall is curved.
 47. The can end of claim 46 wherein the bead includes a bead inner wall, and a curved connection between the bead inner wall and the bead outer wall;
 48. The can end of claim in 47 wherein the bead inner wall is curved.
 49. The can end of claim in 47 wherein bead inner wall and bead outer wall are in contact.
 50. The can end of claim in 47 wherein bead inner wall and bead outer wall are spaced apart.
 51. The can end of claim in 47 wherein the bead inner wall smoothly merges into the curved panel wall of the center panel.
 52. The can end of claim 43 wherein the wall includes a chuck wall that is inclined between approximately 20 degrees and 60 degrees.
 53. Shell tooling for forming a beverage can end comprising an inner center panel tool adapted for contacting a side of a metal blank that corresponds to an interior of a can end center panel, the inner center panel tool including a center portion and a downwardly sloped (dependent claims: smooth curve, straight section, straight section with curve at junctures with the panel wall portion); an upper tool opposing the lower tool and adapted for contacting an upper side of the metal blank; opposing wall tools adapted for contacting at least a chuck wall portion of the blank; the tooling forming a recess immediately above the curved panel wall portion, whereby the recess is adapted to enable a radially outwardly oriented bead to be formed in the blank upon actuation of the tooling.
 54. The tooling of claim 53 wherein the lower tool further comprises a landing located radially outwardly of the sloped panel wall portion, and wherein the landing forms a portion of the boundary of the recess.
 55. The tooling of claim 54 wherein the panel wall is sloped.
 56. The tooling of claim 53 further comprising an outer ring that is adapted to cut sheet metal to form the blank.
 57. The tooling of claim 53 the upper tool forms an upper boundary of the recess and the lower wall tool forms an outer boundary of the recess.
 58. The tooling of claim 53 wherein the wall tooling include a lower wall tool that includes a chuck wall portion and a seaming panel portion, an inner upper wall tool opposite the lower tool chuck wall portion, and an outer upper tool opposite the lower tool seaming panel portion, the inner upper wall tool capable of moving downwardly to form at least a portion of the chuck wall.
 59. The tooling of claim 58 wherein the wall tooling includes a chuck wall portion that is inclined at an angle of between 20 degrees and 60 degrees.
 60. A method for forming a beverage can end comprising: i. providing shell press tooling that includes a lower tool having a center portion and a downwardly curved panel wall portion, an upper tool opposing the lower tool, upper and lower chuck wall tools, and opposing outer tools; the curved panel wall portion of the lower tool forming a lower boundary of a recess; ii. moving the upper tool downwardly relative to at least the lower chuck wall tool to form a center panel and an annular chuck wall from a metal blank; iii. after the moving step i., moving the lower tool upwardly against an underside of the center panel to reform an annular bead between the chuck wall and the center panel such that center panel includes a panel wall curving downwardly at the periphery of the center panel and connected to the bead.
 61. The method of claim 60 further comprising the step of moving the outer tooling relative to an outermost ring to cut sheet metal to form the blank.
 62. The method of claim 60 wherein the step ii of moving the upper tool draws the metal blank.
 63. The method of claim 60 wherein the lower tool includes a landing, the landing forming a portion of the recess.
 64. The landing of method 63 wherein the upper tool forms an upper boundary of the recess and the lower chuck wall tool forms an outer boundary of the recess.
 65. The method of claim 64 wherein the recess enables the metal material to form a radially outwardly oriented bead upon actuation of the lower tool.
 66. The method of claim 60 wherein chuck wall tools include a lower chuck wall tool, an upper chuck wall tool, and an upper seaming panel tool, the chuck wall tool moving downwardly to form at least a portion of the chuck wall.
 67. The method of claim 66 wherein the lower chuck wall tool includes an upper portion opposing the upper seaming panel tool and a lower portion opposing the upper chuck wall portion.
 68. The method of claim 66 wherein the upper chuck wall tool is inclined at an angle of between 20 degrees and 60 degrees.
 69. A lightweight beverage can end comprising: a peripheral curl; a wall extending inwardly from the curl; an annular bead extending radially outwardly from a lower portion of the chuck wall; an center panel having an approximately flat central portion and a panel wall sloping downwardly at the periphery of the center panel and connected to the bead.
 70. A can end for a can for pressurized contents, the can end being configured to be joined by a peripheral annular joining portion to one axial end of a can body of the can and having an outer side arranged to face outwardly from the can and an inner side arranged to face inwardly into the can, the can end comprising: a central panel; a panel wall annularly surrounding the central panel and extending axially inwardly and radially outwardly from the central panel; an annular chuck wall structure extending radially- and axially-inwardly from the joining portion; and an annular rib which is connected between the panel wall and the chuck wall structure and which is concave with respect to the outer side of the can end and extends at least partially radially outwardly with respect to the radially inner edge of the chuck wall structure, the annular rib having a radially inner wall, a radially outer wall, and a curve based located between the rib inner wall and rib outer wall; wherein wall portions adjacent inner and outer ends of the concave annular rib form a rib mouth that is open towards the outer side of the can end; and wherein the end is configured such that upon exposure to high internal pressure, an upper portion of the rib inner wall that is distal from the rib base moves radially upwardly relative to an upper portion of the rib outer wall that is distal from the rib base.
 71. The end of claim 70 wherein the rib inner wall moves upwardly together with the panel wall and center panel. 